Rapid and definitive diagnosis of cardiac injury, including ischemia and infarct, is challenging. Patients frequently arrive at the emergency room with non-specific symptoms, which have a broad differential diagnosis. In most cases of chest pain, cardiac etiology must be ruled out. This necessitates a large number of lengthy and costly tests, and extended stays in overcrowded emergency rooms (ERs). In a 2006 study, Christenson and colleagues analyzed a group of 1819 patients at the ER with symptoms typical of acute cardiac injury. Of these, only 22% were experiencing cardiac injury. However, of the patients without an adverse cardiac event, up to 71% were either admitted to hospital or spent more than 3 hours in the ER. This represents a significant drain on the limited resources of the healthcare system, and exacerbates the nationwide problem of overcrowding and long wait times in the nation's ERs. More importantly, over 5% of patients who were undergoing a significant cardiac event were misdiagnosed and discharged without intervention. Pope and colleagues showed that missed diagnoses of cardiac events leads to increased risk of 30-day morbidity and mortality. They reported a risk ratio of 1.9 for mortality of patients who were not hospitalized versus patients who were hospitalized following acute cardiac injury.
Therefore, there is provided a method and apparatus for a novel interferometric localized surface plasmon resonance (ILSPR) sensor which overcomes some disadvantages in the prior art.